On a geologic map,if the contacts between sedimentary rock units form a series of parallel lines,with the youngest unit in the center,the underlying structure is a ________.

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If sedimentary rock units form a series of parallel lines, with the youngest unit in the center, this is indicative of a horizontal syncline. In a syncline, the layers of rock are folded downward into a trough or basin shape, with the youngest layers in the center. The parallel lines on the map represent the contacts between these layers of rock. An anticline, on the other hand, would have the oldest layers of rock in the center and the youngest layers on the outside. Plunging structures have tilted axes, which would not result in parallel lines on a geologic map.

On a Geologic Map,if the Contacts Between Sedimentary Rock Units